There are numerous options to how to integrate your LOB systems with SharePoint. The answer tends to depend on who you ask, as SharePoint experts will tell yo to use BCS, Microsoft oriented consultants might recommend WCF /AppFabric and SAP consultants will tell you to go with Duet. The right approach depends of course on the actual business requirements. In this article I I will try to summarize the different approaches and highlight their pros and cons.
Business Connectivity Services (BCS)
BCS provides the only way to integrate with SharePoint on a native level. A model is setup to transform the back-end data to lists and items that SharePoint is based on. In the simplest cases all you need to setup a connection is SharePoint Designer but for more complex data structures or for non-standard interfaces you will need a developer to do the work. There are no real limitations in the framework but it is notorious for requiring much unproductive implementing and maintenance effort. Changing a model later tends to break the external lists and other components depending on it, forcing a “plan first” approach for the development. BCS always forwards all calls to the data source directly and does not support caching (other than for Office clients), which might be something to consider if you have a distributed global environment. Any more complex functionality is only available through the API directly and many of the features users are custom in lists are not available for external lists. It is possible to customize also the presentation of the data on a detailed level requiring of course deep knowledge of SharePoint. Many OOTB web parts and functionality like the search and content queries are directly supported. You should see these features as benefits or drawbacks depending on you needs.
Duet is more a concept than a product. SAP and Microsoft have worked together to a solution that solves many of the tricky parts like security when integrating SAP and SharePoint by utilizing the standard services in both ends. Duet is by no means an OOTB solution. On the SAP side Duet introduces an additional layer to support SAP partner developments. On the SharePoint side BCS is used to connect to the custom web services setup on the SAP side. Technology wise Duet offer very little new so companies considering Duet should evaluate the real benefit of the product. As the concept is dependent on BCS also the before mentioned considerations apply.
An often forgotten option is the use of a ESB or middleware solution. Many middleware products offer OOTB or 3rd party adapters for e.g. SharePoint and SAP. By introducing a middleware the IT organization can avoid the burden of maintaining numerous point to point solutions and improve on the visibility of available services and make reusing them is more easy.
When planning to integrate systems with SharePoint, first ask your self if integrating the data with SharePoint brings true business value or if the actual need is only to use SharePoint as a web front-end and bringing the information where the users are already collaborating. When a consultant recommends one or the other of the technologies mentioned here, challenge them to justify the the benefits against not for future but current needs – the only thing certain is change and it does not benefit to put an effort on something that only might be of value in the future.